Field of the Invention
The present invention relates to a dispersant and a method for producing the same, an ink, and a method for forming an electro-conductive pattern.
Description of the Related Art
Conventionally, photolithography, etching, etc. have been used as methods for forming an electro-conductive pattern such as a trace and an antenna on a substrate. However, these methods are problematic in terms of the number of steps in the process, efficiency of use of materials, etc., and also costly.
Hence, there is known a method for forming an electro-conductive pattern by using a printing method such as an inkjet printing method (e.g., see Japanese Patent Application Laid-Open (JP-A) No. 2008-60544).
The inkjet printing method is a method of printing an ink on a substrate according to an inkjet method, and then drying and calcinating the ink.
As an ink, a nano metal ink in which metal particles having a primary particle diameter on nm order are dispersed in a dispersion medium is known.
For example, as a method for forming an electro-conductive film, there is proposed a method that includes a step of depositing a film containing a plurality of kinds of copper nanoparticles on the surface of a substrate, and a step of exposing at least a portion of the film to light to impart electro-conductivity to the exposed portion (see Japanese Patent Application Laid-Open (JP-A) No. 2010-528428). The film is deposited from a solution that contains a solvent and a dispersant.
However, the proposed method has a problem that the volume resistivity of the exposed portion will be high. Therefore, it is requested to provide a dispersant that enables formation of an electro-conductive thin film or pattern having a low volume resistivity.